Java For Dummies Quick Reference

Pattern Class

Package: java.util.regex

The Pattern class represents a regular expression that has been compiled into executable form. Pattern objects are used in conjunction with the Matcher class, which lets you match strings to a compiled Pattern object.

The Pattern class doesn’t have a constructor. Instead, you create an instance of the Pattern class by calling the compile method.

Methods

Method	What It Does
static Pattern compile(String pattern)	Compiles the specified pattern. This static method returns a Pattern object. It throws PatternSyntax Exception if the pattern contains an error.
Matcher matcher (String input)	Creates a Matcher object to match this pattern against the specified string. For more information, see Matcher Class.
Static bool matches (String pattern, string input)	Compiles the specified pattern, and then attempts to match it to the specified input string.
String[] split(String input)	Creates an array of strings that are split from the input string using the compiled pattern.

Here’s an example that matches a simple pattern against an input string:

String regex = “b{aeiou}t”;

Pattern p = Pattern.compile(regex);

String input = “bat”;

bool result = p.matches(regex, input); // true

Here’s a similar example that uses the matcher method to return a Matcher object, which is then used to match the string:

String regex = “b{aeiou}t”;

Pattern p = Pattern.compile(regex);

String input = “bat”;

Matcher m = p.matcher(input);

bool ...